A semiconductor laser source has excellent compactness and conformance to highly integrated semiconductor devices. In late years, a wide-bandgap semiconductor material opens the way for developments of higher-power semiconductor laser sources with an oscillation wavelength of up to the ultraviolet range.
A magnetic-semiconductor laser source has been known for quite some time (for example, the following Patent Publication 1). There has also been known a semiconductor laser source capable of generating a circularly polarized laser light having a specific polarization direction.
For example, the following Patent Publication 2 discloses an optical semiconductor device in which an electrode made of magnetic material or magnetic electrode is provided on the upper or lower side or on both upper and lower sides of a semiconductor element with a p-n or p-i-n structure having an active region therein, and a spin-polarized electron or hole is injected into the active region through the magnetic electrode.
The following Patent Publication 3 discloses another optical semiconductor device in which a spin-polarized electron is injected into semiconductor layers forming a heterojunction, through a magnetic layer to induce the recombination between the injected spin-polarized electron and an unpolarized hole so as to oscillate a circularly polarized light. This device is intended to modulate the polarization state of an incoming light by inducing the magnetization reversal in a magnetic material using an external magnetic field.
The following Patent Publication 4 discloses still another optical semiconductor device in which a ferromagnetic layer is joined to at least one of a p-type contact layer and an n-type contact layer to facilitate the creation of carrier population inversion in an active region.
Further, the following Non-Patent Publication 1 discloses a spin-control semiconductor laser source in which either one of two excitation lights formed as right-handed (σ+) and left-handed circularly polarized lights using a wavelength plate is selectively emitted onto a conventional surface-emitting semiconductor laser source to allow the laser source to oscillate two kinds of circularly polarized laser lights.
Patent Publication 1: U.S. Pat. No. 3,986,194—specification and drawings—(Japanese Parent Publication No. 52-36832)
Patent Publication 2: Japanese Parent Laid-Open Publication No. 06-260725 (Japanese Patent No. 2708085)
Patent Publication 3: U.S. Pat. No. 5,874,749—specification and drawings—(Japanese Parent Laid-Open Publication No. 09-501266)
Patent Publication 4: Japanese Parent Laid-Open Publication No. 10-321964
Non-Patent Publication 1: H. Ando, et al. Appl. Phys. Lett. 73 (1998) 566